This invention relates to a pilot screw. More particularly, the invention relates to a pilot screw with small torsion, excellent leading and excellent balance.
Referring to FIG. 1, a conventional screw has a head 10, a shank 11, a spiral thread 12, and tapered cutting surfaces 13 at the end of the shank 11 can drill a hole also. However, it is very difficult to form cutting surfaces on the thread. Since the strength of the screw is reduced while the cutting surfaces are formed thereon, the quality of the screw is worsened.